Tunnel kiln



Dec. 29, 1931. w. HANLEY, JR

TUNNEL KILN Filed June 7, 1929 9 Sheets-Sheet 1 Dc. 29, 1931. w, l HANLEY, JR 1,838,672

TUNNEL KILN Filed June fr, 1929 9 sheets-sheet 2 Dec. .29, 1931. w. L.. HANLEY, JR

TUNNEL KILN Filed June 7; 1929 9 SheetsSheet 3 INVENTO if" Dec. 29, 1931. w. L. HANLEY, JR

TUNNEL KILN Filed June '7, 1929 9 Sheets-Sheet 4 SLT www AWN ORNEY INVNT-r Y Dec. 29, 1931. w. HANLEY, JR

TUNNEL KILN Filed June 7, 1929 9 Sheets-Sheet 5 J.' Il

mwN

Lf INVENTOR* Dec. 29, 1931. w. L. HANLEY, JR 1,838,672

TUNNEL KILN Filed June '7, 1929 9 Sheets-Sheet 6 & l VEN-ron @i EMU xma@ ATToRNEY Det. 29, 1.931. w, f HANLEY, JR I 1,838,672

TUNNEL KILN Filed June 7, 1929 9 Sheets-Sheet '7 @gli 1,07

l limb 155 Y INVENTOR BY l @ruw www5-jm? ATTORNEY Dec. 29, l1931.

w. l.. HANLEY, JR 15838,(572

TUNNEL KILN Filed June '7, 1929 9 Sheets-Sheet 8 ATTORNEY Patented Dec. 2479, 1931 Y WILLIAM-Lim materias., or isiianronn-1innnsitvmne TUNNEL 'K11-Idir'- l Aupplficat'ioii filed June '-7,

My invention-fconsists.initlievnovel features hereinafter described, reference beingA had te; the accompanying drawings- Which illustrate: severalembodimentsv off the invention 5 Selected-f byamef fon purposes otillustration, and the said invention is fully disclosed in-` the f followingV` description .and claims.

`My invention is; an improvement in'tunnel kilns and is equally applicable tosingl'e 10 tllhel kilns andftwin; tunnel kilns,l and-While it is particularly desirableande eijca'cious. in the; constructionof tunnel kilns for burning bricks and other-coarseclay productst may be advantageously employed forV otherV pur- I5 poses. A .t Y

In. Carrying` mypresent invention into eii'ect,- cause` the Ware When-it enters the kiln-ite pass tlirougli:afpreliminary treat# ment zone,-,Which-` I termthe preheating Zonef7 freinwhich it passes through a.. cen trally `located tiring zone,A o-n'vleavving; ywhich itl passes through acooling zone. It will? be understood that in accordance with usual practice the bricks or' 'otherv :coa-rse 4clay prod-` nets as theyconie `fromfthe forming machine are treated in a suitable drier for-'the eliminaton oii the greater part of the occluded Water, and that after leaving the drier they areinune'diately introduced into'th'e preanrive-'at afteinperature approximately 3000 F. In the preheating Zone they Wareis raised intemperature from about- 300O l?.k to 12000 F. or 13000K, at which temperature it enters the burning Zone Whereit is raised' toapproximately '19009 F.,A thence passing:l into.. the cooling -zone'` Where it is cooled from approximately 19000 F.,-clown co-5009.1?. or GOO-O F. AIn-theA preheating of the Ware itis necessary not only to raise the temperatnre ot the ware, but in addition,.to provide ar Vsutlicient quantityoi oxygen for theoxidation. of sulphur and other oXidiZable matter in the clayland it is essential to the successful operation of preheating 'that the' fumes and vapors resulting romf-this chemical action shall be removed from the pr-elieatingfzm rapidly as' they are coloration off the Ware.

heating zone of the tunnel lriln7 inv which they formed in order toepreventgsculnlning or dishr -f 'eration oi tunnel kilns, ziert-enables mef-to 1929. serial: No.1 369,090.

In carrying Amy inventonfnteeeett l Y provide for-theadmission; at-emoreorf lessA closely related-points longitudinally ofthe preheatingpzone oi.l iig hly. lieated freshair,

means being;- provided for regulating4` the T amount of-heated-Vairfadmittedat; anyzpoint longitudinally there0 so that any desired range 0ftemperaturesf generally termed. e, temperatura curve?" .may be -securedfand maintained, Iffnrtherprovide meebenee'l mea-ns With-n the pI-ieheati-ngfZOneI-leeetedi et closely l adj .aci-int points ,longitlldinally` thereoi?,` preferably: in the ferm-- of. a'. longitudinal servies, ofgrotar-y-` fans, ,located at onen side: of tbe Pethl. ef. the-Were Q11-l tbe-transferable means orears, and-:preferably yeen ille-bettemV portions Ofi the steeks bricks er other prefluets:0n-seid;transferrllgmeans, whereby the heated-air: will be -fere-bly @insulated trensrerselythreugb the lewer perl-ien 0f the st aclrsf off Ware; vfrom one-AsideV of thel preheatf inail-Zehe.' le the. when. the: fees-er other air moving. mea-ns., being located adjacent to the 11o-iat at whchthe heateda-rent-,ers the Vpreheating-zfone and having; larger capacity is; necessary tVV insure the: dre-Wngin; of, tbe required amounts ef heatedLei-r-tbereby efft'eetng-a reereulaton of4 this heated; ein with.h in, the pre-heating zone and iereibly ejeetng ittb-ereffromf threugh suitable; eiltlet; perte provided usually. oni-the opposite sident the preheatingf zene fremtbe fans. By. this means I amablete obte; i-avigoreus Gir-e11- latoaofthe heatedr air t ughans'l erben@ the-:bricks or-other'products, the ,freshar v from the: :Ea-ns passing-between and amend the Ware tbe; -le-Werf layers'ef were en :the ears in: a-Ql-ireeteritfanstersely' O ftlte kiln and passi-ns: in tbereverseV dreetienf between and around. the were irl;- tlie upper layers and over the top ofthe were, preventing-the cumulaton et stagnant gases adjacent tothe surfaces ofthe Werft-andeneblinsthe Gerben and sulphur- Other oxidiZ-ablemetter to be eliminated yWith` mitch greater rapidity thanrcan-be accomplished where this:vigorous and sweeping Qi-rculationwand recireulation' is not providedf-Thisis a -n-Iatterjof area-t imnertanee inthe' een-struction and en: m

materially shorten the length of the preheating Zone thereof, and reducing the cost of the kiln accordingly. lt will be noted that construction does not merely circulate the atmosphere of the kiln or zone, but provides for continuously introducing fresh air for oxidation and the continuous elimination of theiair in the kiln or Zone, together with the gases and vapors evolved in the preheating and oxidizing of the ware, thus efficiently removing sulphur, carbon and other oxidizable and vaporizable materials from the ware.

The heated air for use in the preheating Zone as before described is preferably obtained, in accordance with my invention, by admitting fresh air atclosely related points longitudinally of the cooling Zones of the kiln under the control of suitable regulating means or dampers at each of said points, which is heated by Contact with the fired ware moving through the cooling zone from the tiring zone, and is then withdrawn from the cooling Zone at separated points longitudinally of the cooling zone by the fans or other air forcing means in the preheating zone, the amount of air withdrawn from the cooling zone at each of said longitudinally disposed points and admitted to the cooling Zone being under regulation of the regulating means or dampers previously referred to, so that the heat of the fired ware is conserved and used for preheating oxidizing and watero smoking the ware, and the range of decreasing temperatures in the cooling zone, at different points longitudinally thereof, represented by a cooling curve can be regulated very accurately to give any desired cooling curve. It will follow, of course, that the total amount of heat units taken out of the cooling zone will always equal the total amount of heat delivered into the preheating zone less radiation and conduction losses, but by means of the regulating devices which control the 'admission of cool air to the coo-ling zone and the admission of heated air therefrom to the preheating zone in an entirely independent manner, the desired heat curve can be maintained in the preheating zone and any desired cooling curve can be maintained in the cooling zone, and these heating and cooling curves can be independently controlled andvaried at will. As a result of this arrangement I am also able to reduce the length of the cooling zone and still obtain efficient' cooling accompanied by the heating of the necessary air for the preheating zone.

The tiring zone of my improved kiln may be of any type which will permit and not interfere with the operation previously indicated with respect to the heating and cooling zones. I prefer to employ a firing zone in which the ware is directly fired. that is to say comes directly into contact with the products of combustion, which however must be essere prevented from entering either the preheat; ing or the cooling zone, so that there will be practically no end iow of the products of combustion from the firing zone in either direction.

My invention also includes the novel features of construction and combination of parts hereinafter described and particularly pointed out in the claims.

In the accompanying drawings in which l have shown several embodiments of my invention for purposes of illustration,

FigQ l is a diagrammatic plan view of a twin tunnel kiln embodying my present invention.

Fig. 2 is an enlarged horizontal section partly broken away of one end of the kiln shown in Fig. l, containing a preheating zone for one line of cars and a cooling zone for the other line of cars of ware arranged side by side.

Fig. 3 represents an enlarged transverse vertical sectional view taken on line 3-3 of Fig. 2.

Fig. 4 is a similar'sectional View on line 4 4 of Fig. 2.

Fig. 5 is an enlarged transverse vertical sectional view through the firing zones.

Fig. 6 is a plan view showing a single tunnel kiln embodying my invention.

Fig. 7 is an enlarged horizontal section of the preheating zone and a portion of the liring zone of a single tunnel kiln embodying my invention7 partly brokenaway.

Fig. 8 is a similar view of the cooling Zone and adjacent portion of the firing Zone of the single tunnel kiln illustrated in Fig. 7, partly broken away.

Fig. 9 is an enlarged transverse sectional view through the preheating zone on the line 9-9 of Fig. 7.

Fig. l0 is a similar section on line 10-10 of Fig. 7.

Fig. 1l is a similar section of the cooling Zone on line l1ll of Fig. 8.

Fig. 12 is a transverse section through the firing zone.

Fig. 13 is a detail view showing a slight modification of the driving means for the fans.

Fig. 14 is a sectional view similar to Fig. 3. showing a slightly modified construction of twin tunnel kiln embodying my invention.

Fig. i5 is a sectional view similar to Fig. 3 showing my invention embodied in a unitary twin tunnel kiln, in which there is no central wall or partition throughout the kiln, or at least throughout the end portions thereof at opposite ends of the firing zone.

Referring to the embodiment of my invention in a double tunnel kiln structure illustrated in Figs. l to 5 inclusive, I have shown in ig. l a plan view of the entire kiln, and in Fig. 2 a partial plan view, both views being partly broken away, the kiln structure the kiln, indicated at' A, constitutes aduplex firing chamber containing tvvo firing Zones, A1 and A2. Eachof the end 'sections'ot'fthe kiln, which' are indicated at B and"B1 respectively, comprises a preheating zone, in-

dicated atl), and va cooling zone, indicated at C, arranged side by side and separated by the centralpartition Wall, 3. Each "of the end sections, B, is also provided with aterminal portion,'indicated`a-t B2, B3 respectively,'hav.

I solid side Walls and a solid partition Wall, 20

3a, forming a continuation of the central partition Wall, 3, and provided at the outerl end with doors, indicated at-8-8, the sections', B2, B3, forming vestibules for the reception and discharge of cars of Ware at opposite ends of the kiln. A vline of tracks or rails, indicated at 9' and 9a respectively, extend longitudinallythroughout the length of each tunnel of the kiln, on which it vvillbevunderstoodthat the cars, 10, loaded Withy stacks of bricks or other Ware are propelled, the, cars on one set of tracks moving inthe opposite direction toV that in which the cars onv the other set of tracks are moved. It Will 'be understood that each tunnelV is occupied by an entireline of cars-Which are'moved'longitudinally by the insertion at the entering end of a fresh caror" Ware from the drier, which as it is pushed in `forces out aV car containing `tired and cooled vvare romthe other end Vor' the tunnel. The directionfof movement oi' the cars on the tracks or rails, 9 and 9a respectively, are indicated by arrows in Figs. 1 and"2.

It will thus be seen that the cars loaded Withnnlired ware from the drier are'passed longitudinally through one of the preheating Zones, P, one of the firingjzones, A1 or A2,"and

one 'of the cooling zones,'C, before being discharged, land that in each end .section of the kiln therevvillbe la line oi cars passing in one direction through the preheating zone to the firing zone connected therevvitlnvvhile on the other side of the partition vvall, 3, there Will be a line of `cars loaded .With highly heated Vfire Ware, moving'in the opposite direction from the communicating firing Zone for that tunnel and 'being gradually cooled. `As the end sectionsyB and B1, at opposite ends of l thetunnel are cons'tructedin exactly the saine manner, a description of the construction and operation of one of such iend'lsections will serve for both. f

4The exterior side Wall 2, for example, of thecooling zone, C, is preferably provided with a plurality `of air inlet apertures, indicatedat- 11, seeFigs; `2 and-4? Whichf are' loicated `at intervals longitudina 1yV of thewall andh-ave'their inner ends approximately adjacent-to the-level of the top or supporting Vsurface, ofthe can-Which ispreferably formed otreiractory`-` material and provided with' longitudinallyof thecooling zone, and therebyany desiredfrange or curve of cooling temperatures may be accurately maintained; The

central partition Wall,v l3,-is provided with a plurality ofi outlet 4ports,.indicated at'13 in Fig. 3,"Which are preferably arranged out of transverse alignment with the air inlet ports,

11. These outlet ports, 13, communicate by d vertical-passages, 14, inthe partition Wall, 3, and by horizontal communicating passages, indicated'at 15, beneath the adjacent tunnel containing preheating zone, P, with vertically disposed pass-ages, 16, located in the outer Wall, 1, or between it and a partition Wall, 1a, separatingthe passages, 16, from the portion ol the preheating-zone occupied bylthe cars, as shown in Fig. 3 for example. In any case eachl of the vertical-passages, 16,-Which il are located at intervals longitudinally of the preheating zone, communicates With the intake sidey of a fan or airmoving device, 417, -revolving on a'horizontal axis and arranged to discharge the air admitted-through the adl jacent passage, 16, transversely through'the lovver'portionof the stack of Ware carried on the adjacent `car.`l In this instance I have shown la series of rotary-fans., 17, extending the entire length ofthe preheating zone along "f vthe outer side thereof'and located immediately above the partition-Wall, 1a, so that the lower edges of the fans are substantially in alignment Withfthe top of the goodssupportfing portions of the cars, and each fan will act "I to Withdraw heated' air from one (or more) of the outlet Vor eduction ports, 13, of the adjacent cooling zone and discharge it through the lower portion of the Ware The fans are conveniently supported by horizontal shafts, i

1'8, mounted-in bearings, 19, located and supported-outsideot the kiln Where they will not be exposed to the higher temperatures Within the kiln. These fans may be driven in any desired manner,= for example from `a longi- L tudinal-driving shaft,indic'ated at'20, extending the length of the preheating'zone and provided'with` pulleys, 21, each of which vis connected lby a belt, '22, with a pulley, 23, on one of the fan shafts, V18. The-fans are conveniently lmade of any suitable material, as a metal'falloypcapable of "withstanding the high"temperatures to Which they` are exposed linthe preheating zone. il, preferably make each `dan', 17, of' greater 'capacity than is irequired to Withdraw7 the air' from the adjacent cooling zone through the passages, 16, 15, 14, and port, 13, so that after the air is discharged horizontally through the Ware, as indicated by the arrows, in Fig. 3, it Will pass upwardly and be drawn back. through the upper part of the stack of Ware and over the top thereof, as indicated by the arrows, y, returning to the fan through the upper part of the space, indicated at 24, above the partition Wall, 1, and vertical passages, 16, so that the air will be recirculated and caused to pass more than once through, around and in contact with the Ware. The partition Wall, 3, is also provided With a plurality of eduction ports, 25, opening from the preheatingl zone and communicatingby vertical passages, 26, in the partition Wall, and horizontal passages, 27, in the concrete base or foundation With an eduction Hue, 28, preferably located entirely outside of the kiln and connected to a suction means, as a stack or suction fan, for example. ln this instance the flue, 28, is shown as connected with a stack, 29, through which the air after it has served its purpose of heating, Water-smoking and oxidizing the Ware, together With the gases and vapors resulting therefrom, is discharged into the atmosphere or otherwise disposed of.

I also provide separate and independently operable dampers for controlling the admission of heated air to the preheating chamber through each of the vertical passages, 16, for example by a series of horizontal dampers, 30, (one of which is shown in Fig. 3) in the form of blocks which may be operated from the exterior of the kiln to control the passages, 16. I also prefer to provide each of the eduction passages, 2T, With a damper, as the vertically movable dampers, one of Which is indicated at 31 in Fig. 4. The eduction ports, 25, for the preheating zone are preferably located out of alignment With the adjacent fan or fans on the opposite side, and it will be seen that as the heated air from the cooling zone is being continually drawn into the preheating zone through the passages, 14, 15 and 16, and circulated and recirculated through the ware, all portions thereof Will be brought into contact with the heated air Which is continually in motion as it passes over the surfaces of the Ware, so that the gases and vapors formed by the heating and oxidizing Will be swept away from the surfaces of the Ware as rapidly as formed, bringing fresh portions of heated air into Contact therewith, so that t-he elimination of carbon, sulphur and other oxidizable matter in the clay Will take place much more rapidlj7 than Would be the case if the air Was not circulated in this manner, so that as a matter of fact the length of the preheating zonevcan be materially reduced. It will also be seen that in the pree heating operation the heat curve can be very readily controlled by the operator by means of the dampers, 30, so that more or less heated air can be delivered by each of the passages, 16, according to the regulation of the dampers, and in this manner the heat curve can be so arranged as to best insure the elimination of oXidizable matter as sulphur, carbon, etc., according to the character of the material in the Ware. For example in some clays it may be found desirable to raise the temperature quickly in the preheating zone up to a certain point and thereafter raise the temperature very gradually through the remainder of the travel of the Ware therethrough, While in the case of other clays it will be found desirable to raise the temperature very gradually during the irst portion of the travel of the Ware therethrough and thereafter increase the temperature rapidly, or to effect a gradual raise of temperature throughout the travel of the Ware throughout the preheating zone.

In the cooling zone the introduction of fresh atmospheric air into said zone, and particularly where the products of combustion from the firing zone are prevented from entering the cooling zone With the fired Ware, effects the cooling of the Ware more rapidly than otherwise result, and I am also able to control the admission of tiis air, both as to its total quantity per minute and also to admit the air in larger quantities at certain `portions of the cooling zone than at others, by means of the regulating valves or dampers, 12, so that any desired range of cooling temperatures or cooling curve can be maintained, and the Ware may be cooled more rapidly at certain portions of its travel through the cooling` zone than at other portions, if desired. In other words, the temperatures of the cooling zone throughout its length is under the direct control of the operator and can be suited to the particular character of the Ware, to give the best results. It Will also be seen that the adjustment of the dampers, 12, does not have to correspond at all With the adjustment of the dampers, 30, controlling the admission of the heated air to the fans in the preheatng zone, as the eduction ports, 13, will deliver the air to the preheating zone in accordance with the setting of dampers, 30, regardless of the setting of the dampers, 12. The operator, therefore, has entire control of both the preheating and cooling operations, and the heat of the lired Ware is recovered and employed in the preheating zone. Of course it will be necessary to so adjust the dampers, 12, that a total amount of air may be admitted to the cooling zone suflicient for the requirements of the preheating zone under the control of the dampers, 30, but this can be very readily arranged. Moreover the arrangement of the inlet ports, 11, and the eduction ports, 13, for the cooling zone on opposite sides of the ware and adjacent to the level of the supporting surfaces of the cars `results ina very thorough circulation of therair around and through the Ware stacked thereon, asthe heat imparted to theiair from contact with fthe heated Ware causes it to rise through .and around the Ware and become .more andinore vhighly heated, While tlielocation yoft-he eduction :ports through ".vhichfit Vis sucked out .by the fans, `1"?, in the zpreheating zonejwill. drawfthe l1eateclair .downward .and carry it outthrou'gh the connecting passages. In practiceit is found that the eliiciencyof this cooling. zone is such that its length .may be decreased to substantially the same extent las Athe length of the preheating zone, thereby effecting further economy `iii the construction ofthe ltiln.

l As before stated, thefamount of heat units taken out of the cooling `Zoneby the lair Will ,1. be equal to the total amount of heat units suppliedto the preheating Zone less radiation and conduction losses,` but as the. risefrin temperature in the 1preheating `Zone is substantially 900 degrees Aor. 1000 degrecspthat is tof` say 300 F. tto 120091?. or1300 F., Where as'the drop of temperature in the cooling-zone` is approximately from 1900O `F.,.to"`500fJ F. =or 600o F., or about 1400 degrees., a suliicient amount vof heat for 4.preheating will always be supplied"'from` the coolingzone regardless.

`of ordinary losses by radiation, etc. ln Fig'. `5, I have shovvn one form of firing Zone which may be `conveniently employed.

in connection with v,the .preheating .and cooling zones constructed aslcpreviously described The particular construction ofthis 4firing Zone 'isV substantiallysimilar to that shown, in my former Letters 'Patentof,thev United States,

No. 1,652,570 dated December 13, 1927.1and

2. will not be specifically kclaimed herein. :The

,central portion, A, of the kiln betweenlth two end sections, B and VB?, both of which are constructed Aas previously described, with the relative l.positions of the preheating and p Vcooling Zones reversed, as' indicated at P? and Cl in ig.'1, consists of a duplex/firing chamber containing tivo firing zones, A1, A2, separated Uby a portionv of the central partition wall, 3, which as fshorvvn herein .is imperforate and flueless. Each firing zone 'is provided with a row of 'furnaces arranged-along its outer Wall and arranged for direct firing. ln this instance have shown gas furnaces comprising the burners, 35,`suppliedivvith gas i or other hydro-carbon fuel by a main fuel "pipe, 30, and branches, and With air by a main air pipe, 37, .and branchesthe branch air and gas pipes being provided with m'dependently adjustable. controlling valves, 1n-

` dicated atSSand 39 respectively, so that each furnace Way be independently'controlled.

Fedeli of the heating zones is provided on the side of the goodsuspace adjacenttotheffurnaces With a longitudinali extend-ingbag Waller deflecting `Wall, linc icated at 40, jtlie cal passages,4l,are formed between the outer .Wallfofthe furnaces and the bag Wall, so that .the products of combustion from the furnaces l are. carried upwardly over the topv of the bag .wall .and .discharge downwardly `upon and through the Ware. Each firing Zone is also provided with means for positively v withdrawing .the heated products-of combustion after .they have given upthe greater portion of .their heat to the Ware, and this is accomplished ,conveniently `by means of Veduction ports, 4&3, in the Vinner face of the bag Wall, 40, approximately .at about the level of th'e supporting surfaces of the cars, Which'ports are connected by eduction passages, 44, with a longitudinally extending eduction flue, 4,5. yThese eduction passages, 44;, conveniently ex- `tend `through solid `masonry portions, connecting the `bag Wall with the outer Wall of thefliring zone ,between the vertical passages 4el, as indicated at The-eduction ports or passages, 44, are alsoeach provided with va `,controlling valve, 46, so that throughout ,theV length of eachy firing, zoneV the Vadmission of .heated productsof combustion from each furnace is under directand inde endent-control, and the heat-ed .products o combustion rafter performing their Workare immediately Withdrawn throughfthe eduction pipes, 44, also under ,independent control. In .order to positively. withdraw the products of combustion,.the eductionflue, 45', is preferably connected Withair moving means, as a stacker suction fan, .and these gases may be employed :fa recuperator, .indicatedattl .operating a. Well knoivnrvvay,` connectedlwith .the e `uc tion iiue, 45, and interposed betvveensaid flue,

,and la suction fan, indicatedat 48, .airbeing admitted ltothe recuperator through the inlet passage, 47?, and discharged through the pipe or passage, 49, which .may be vconnected .for example by Ya pipe`50, with the airppe, 37,

other suitable device. The spent productsfo'f combustion after :leaving the fan,"48, may

pass to a stack, 52, or-to any other. suitable point. Itwill be understood that the gcon- 'struction of each iring z oiie, A1fand.A 2.,.vvill be the same as that ,previously.describedand as showninthedrawings. the cars move in one direction through the..firingzone,Af, and in theoppositedirection through y.the firing zone, A2, the heat curvesfor thefiring Zones will `be.. exactly opposite, .for example,

assuming that the! desired ,temperature at; the rentering'-fendofthe firingzone, .A2, is s ubstantially 1200o F., the `burners and `eduction ports; will be i adjusted tdgive .I the desired iris- 'its Vand by-Lapi,pe, 51, to a drier, not shown, or

ing heat curve as the cars move (to the right in Fig. 1) so as to produce a temperature of substantially 1900C F., at the discharge end of the zone, A2, when the cars pass into the connected cooling zone, C1. In the firing zone, A1, the entering end where the temperature of 1200o F., is to be maintained will be opposite the discharge end of the zone, A2, and the furnaces and eduction passages will be so regulated as to produce the desired rising heat curve as the cars pass to the left 1n Fig. 1, toward the discharge end of the zone, A1, from which they pass into the connected cooling zone, C. The air for-cing means, as the fans, 48, 48, connected with eduction fiues, 4:5, of the respective firing zones will have capacity slightly in excess of that required to Withdraw all the products of combustion discharged into the Zone with which they are connected, so that the products of combustion will not be permitted to iiow endwise into the connecting preheating and cool ing zones which are directly connected thereto without any partition. This prevents the scumming or staining of the ware by Contact of the products of combustion With the Ware before the preheating, oxidation and watersmoking is accomplished, and at the same time avoids interference with the regulation of the preheating and cooling Zones previously described, which would be seriously interfered with by the end flow of such products of combustion. While I prefer to employ the type of firing zone herein' shown an described, I wish it to be understood that other forms of firing Zones may be used in connection with the preheating and cooling zones previously described, and the ware may be red either by direct firing or indirect firing. I also Wish it understood that the improved preheating zone herein shown and described may be employed in other forms of tunnel kilns and supplied with heated air from the cooling zone or other source.

In Figs. 6 to 12 inclusive, I have shown my invention embodied in a single tunnel kiln in which figures the parts previously described and illustrated in Figs. 1 to 5 inclusive are Given the same numerals with the addition of 100. In Figs. 6 to 12 inclusive, the central portion of the kiln represented at A3, is provided with a single liring zone,A4. The firing Zone may be heated by a single row of furnaces arranged along one side, or by a double row of furnaces arranged on opposite sides, as preferred and as shown in the drawings. As the construction and operation of the liring zone, A4, will be exactly the same as 'i that previously described with reference to the. operation of either' firing zone' of the twin tunnel kiln, except that in this case the products of combustion will be discharged into and removed from the kiln at bothsides, it will be unnecessary to again describe the construction and operation of this portion of the single tunnel kiln in detail. In this instance, I have shown the eduction lues, 145, for the furnaces on the opposite sides of the kiln connected to a common recuperator, 1&7, for heating air which is supplied to the burners of both sets of furnaces and to a drier or driers, not shown, or other use. In the'single tunnel kiln, the cars entering the vestible portion, B, will all move in one direction along the tracks, 109, successively through the preheating zone, firing zone and cooling Zone to the vestibule portion, B5, at the opposite end of the kiln. The end portion, B3, of the kiln contains the preheating zone, P2, which is constructed substantially as hereinbefore described, reference being had to Figs. 9 and l0. In this instance the heated air is conveyed from the cooling zone, C2, which is at the opposite end of the kiln, by means of a hot air Hue, indicated at 115, e2-tending past the firing zone and longitudinally of the preheating Zone, and conveniently below the vertically disposed passages, 116, leading to the induction side of the fans, 11'?, and controlled by the dampers, 180, in exactly the same manner as hereinbefore described.

The fans, 117, discharge the incoming heated air directly across the lower portion of the goods space and have suliicient capacity beyond the suction requirements to effect recirculation of the air, as previously described. On the opposite side of the preheating zone are a series of eduction ports, 125, connected with passages, 126, 127, with a longitudinal eduction flue, 128, located preferablyv outside of the kiln and connected with' an exhaust fan or stack. In this instance, I have shown the eduction iiue connected with a stack, 129. The eduction port-s and the passages connecting them with the ,eduction flue are preferably provided with independently operable dampers, 131.

The fans, 117, are shown as mounted on horizontal shafts separately driven from the exterior of the kiln in the same manner as previously described.

In Fig. 11, I have shown a cross-sectional view of the cooling Zone, C2, which is pro vided at intervals along one side With air inlet apertures, 111, located adjacent to the level of the supporting surfaces of the cars, or in other words adjacent to the lower portion of the goods space, and on the opposite side of the cooling Zone are a longitudinal series of outlet ports, 113, connected by passages, 114, with a longitudinally extending conducting flue, 115, previously referred to, which extends lengthwise of the cooling zone, past the firing zone and lengthwise of the preheating Zone, where it is connected with the inlet passages, 116. This flue is conveniently carried throughout its entire length entirely outside of the kiln and pref- :Leonora nerz'rlo'ly -below 'the surface of the ground. I-indl itconvenient, however, to carry it beneath one side of therpreheating zone inthe I'foundations thereof, so that the heated air vmay Iascend substantially vertically through `the inlet passages, 116, to the fans. Itwill beseen-that inthe single tunnel Ikiln the heat-- ed fresh air for'preheating, oxidizing "and water-smoking isA furnished 'from the coolvjing zone,l which is inthisuinstance .located at the opposite v'end of the kiln, but'the operation and eiiiciency 4of the kiln is the `saine faspreviously'described with reference to the twin tunnel construction in which the heated air for each preheating zone is taken from an adjoining cooling zone ofthe lother tunnel.v The air. inlet apertures, 111, may also be provided, if' desired, with dampers indicated `at 112, corresponding-with the =dampers, 12, in Fig. 4,andfthe eductionV ports 'andpassages for the cooling zone are :also shown vprovided with da1npers, indicated at 114@l I may 4use either or both of these series Vof dampers for controlling the admission of air and the eduction of heated air at {difierentfpoi'nts longitudinally of the cool- 'ing zone, so `aslto establish and maintain the y `desired cooling curve. This `independent regulation ofthe portions of thefcooling zone throughoutfits length is, of course, entirely 'independentof the control of the preheating zone to establish and maintain', a rising heat `curve therein, thel heated airfrom the cooling zone being in this instance collected in "the connectinghot air conducting fine, 115, and redistributed'at diiierent points longitudinally ofthe preheat-ing vzone under the control of "thedainpers, 130.V

The operation of thev single'tunnelki-ln will bef-exactly the same as that of each of the `tunnels of the twin tunnel kiln previously described, and it need not therefore be repeated. "It willbe understood that in'bo't'h embodir*ments-of my inventionfa predetermine'dpath of circulation of the heated air in the pre-V -hfeatingvrzone will resultby reason'ofthe'fact thatthe air inlets, (16 or 1116) by whichthe heated air is admitted andjwhich I Vpreterably terinthe initial inlets, and the fans are "located adjacent to the, lower portion off the )goodsspace, and that the fans discharge this lair substantially horizontally in a direction vtransversely of the kiln. 'The heated air dis- Ycl-iarged by these fans, which are located .adacentito the `lower portion of the goods chainber 'will Vpenetrate through the'lower portions of goods on the cars fronione side of the preheating zone to theother, andwillbe "forcedto return in the opposite direction "through theupper portions ofthe goods on the cars, and over the top rofthe goods on the (cars.` The circulation will also be `upward 4and in rear-of fthe fans.

at t-hefside ofthe zone remote 'efr-oni' the fans andv along the side of the kiln :adjacent to herevwill' Yalso be Vi-dizing vand waterfsznoking.

entlyoperable dainpers, (31 or 131) which" some circulation upward through the ware. This eects the most e'cientV circulation along the shortest path or paths by which the air `may thoroughly penetrate the entire carloadfof ware and return to the starting points.

In the ideal Case, there would bea horizontal plane'of tno circulation just above the tops of the fans, below whichv the circulation would be transversely of the kiln away from vthe 'fans and labove which the circulation` would be transversely of the kiln in the opposite direction, toward the fans. This ideal ofcourse can be achieved onlyapproxiinately `on naccount of the construction of the kiln which inust provide a certain amount of space -above the ware,so that a portion of the'return currents toward the fans :willdrift through this space, but-a very' considerable portion of the return currents pass through and around the upper portions of the ware on the cars. There will also be some tendency :for portions ofthe lower `currents to pass upwardly through the ware and get into the return currents flowing in the opposite direction. The :ultimate eiect, however, is to greatly expedite oxidation Vand water-smoking, and to sweep .away the gases and vapors generated-thereby to bring fresh heated air continuously into contact with the ware, and

also to continuously draw ofi3 the air andthe l contained gases and vapors and eliminate the latter from the kiln. As before stated, the increased capacity ofthe fan above its vsuction requirements permitsv of recirculating port-ions of the air whileother portions willA I Vbe discharged through the eduction ports and the-eduction fiue, carrying with them the gases and vapors evolved bythe preheating, ox- The independcontrol the eduction of the heating and 0X- idizing medium co-operate with the dampers, (30 or 130) for independently controlling theV initial lair inlets in regulating not only the heat curve butalso the supply of oxygen for oxidizing the carbon, sulphur and other oxidizable inaterials in the clay, at different points p longitudinally of the preheating zone, so that the elimination of the oxidizable compounds is under accurate control.

the preheating zone may be effected notonly b the dan ners Areviousl described but also y Y l 7 Yby independently controlling the speed'off' VIl() revolution of the diercnt fans located at different points longitudinally of said Zone. This may be accomplished in either' of the embodiments of my invention herein shown, in a very simple manner by changing the relative sizes of the pulleys, (21 and 23, or 121 and 123) so as to vary the speed of different fans in thc series. It is, of course, obvious vthat this result may be accomplished in other ways, as for example by providing each fan with a separate motor, as indicated for example in Fig. 13, in which one of the fans is indicated at 217, having its shafts, 218, connected with an electric motor, 220, controlled by a suitable rheostat, 2202i, so that the speed of each individual fan can be independently controlled where this is found de- Cirable.

It will also be understood that by controlling the introduction and eduction of the heating and oxidizing medium and the speed of the fans, the degree of concentration of contaminating gases and vapors at different points longitudinally of the preheating zone may also be controlled. Obviously if the gases contain too great a degree of sulphur for example, at a particular point, etc., which can he readily ascertained, the remaining sulphur in the ware would not be evolved so readily and the oxidation of the ware would be slowed up correspondingly. In such cases the gases and vapors may be withdrawn more rapidly at this point and more fresh air may be admitted, and the speed of the adjacent fan or fans may be increased if necessary.

On the other hand, if too little sulphur, for example, is present in Vthe waste gases at a particular point in the preheating zone, it would indicate that there is a heat loss at that point, and that air is beinfr supplied, the waste gases are being drawn oli1 more rapidly than necessary, in which case the supply of heated air may be reduced at each point, or the dampers controlling the eduction ports, (31 or 131) adjacent to such point may be partially closed or both.

It will be understood also that the goods space of each tunnel` whether of the single tunnel or twin tunnel kiln, will be separated from the portion of the tunnel below the cars, in any desired or usual manner to protect the wheels and metal bodies of the cars from the heat in the tunnel. This may be conveniently accomplished by means of the usual sand seals, the opposite sides of each tunnel being provided with longitudinal sand receptacles extending the entire length of the tunnel and indicated at GO in Figs. 3, l and 5, and at 160 in Figs. 9, 10, 11 and 12, which are engaged by flanges, 10", (or 1101) depending from the sides of the car bodies.

In Fig. 14, I have illustrated a slightly modified form of twin tunnel kiln embodying my invention, in which ligure the part-s corresponding with those shown in Figs. 1 to 5 inelusive are given the same reference characters with the addition of 300 to avoid repetition.

In this construction the cold air is admitted to each of the cooling Zones through the air inlet apertures, 311, into the space below the cars and is taken up by passa-ges, 311, formed in the central wall, 303, and delivered into the goods space ofthe cooling zone above the supporting surfaces of the cars and int-o contact with the heated ware from the aligned firing Zone, which is to be cooled. This arrangement for the admission of the cooling air possesses the advantages of keeping down the temperature of the metallic portions of the cars and also cooling the portion of the centra-l partition wall, 303, in the lower portions thereof adjacent to the sand seals.

The outlet passages, 313, for the cooling Zone are in this instance located in the outer wall and may be conveniently provided with dampcrs, indicated at 312, the outlet passages, 313, heilig connected by communicating passages, 315, with hot air inlet passages, 316, discharging into the preheating zone adjacent to the suction and circulating fans, 317. In this instance the preheating zone is provided with a plurality of eduction pipes or passages, one of which is indicated at 325, and which are preferably formed by pipes Which extend inwardly from the exterior wall of the preheating zone substantially midway between the fans, 317, and have vtheir inner ends opening into the preheating Zone beyond the pressure face of the fan where the heated air in said Zone is under a. certain amount of compression. These pipes or passages, 325, are connected by passages, 326, with a common eduction liuc, 328, preferably located outside of the kiln and connected to a suction means, as a stack or suction fan, in a manner previously described with reference to Figs. 1 to 5. The hot air inlet flues, 316, for the preheating zone are preferably provided with independent regulating dampers, 330, andthe eduction passages for the preheating Zone may also be provided with regulating dampers, 327. If it is found necessary or desirable, each of the air inlets, 311, for the cooling zone may also be provided with independent regulating dampers, 311", and it will be seen that the independent control of the admission of cold air to and discharge of hot air from the cooling zone, at different points throughout its length, and the admission of heated air from the cooling zone to the preheating zone and the Withdrawal therefrom of said air with the vapors and gases of preheating, at different points longitudinally of the preheating zone, are under the complete control of the operator. The operation of this form of kiln will be exactly the same as that described with reference to Figs. 1 to 5 inclusive, and need not be repeated.

In Fig. 15, I have shown my invention emzone or zones provided with a plurality of initial inlets fora gaseous medium, disposed at intervals along one side of said zone adjacent to the lower portion of the goods space thereof, a longitudinal series of mechanical gas propelling devices located within said zone adjacent to said inlets and con structed to discharge the said medium transversely across the lower portion of said goods space, vsaid zone being provided on the side opposite said inlets and adjacent to the lower portion of the goods space with a series of outlet ports for delivering the said medium xtogether with gases and vapors of preheatfing from said zone, means for supplying an oxidizing gaseous medium to said inlets, said gas propelling devices having sufficient capacity to effect the return of said medium transversely across said zone at a higher level, and the recirculation of said medium within the main chamber of said zone, before it passes through said outlets, and means for supplying an oxidizing gaseous medium to said inlets.

5. A tunnel kiln having its preheatinrr zone or zones provided with a plurality o initial inlets for a gaseous medium, disposed at intervals along one side of said zone adjacent to the lower portion of the goods space thereof, a longitudinal series of mechanical gas propelling devices located within said zone adjacent to said inlets and constructed to discharge the said medium transversely across the lower portion of said goods -space, said zone being provided on the side opposite said inlets and adjacent to the lower portion of the goods space with a series of outlet ports for delivering the said medium together with gases and vapors of preheating T from said zone, means for supplying an oxi,

dizing gaseous medium to said inlets, said gas propelling devices having sufficient capacity to effect the return of said medium trans- A versely across said zone at a higher level, and the recirculation of said medium within the main chamber of said zone, before it passes through said outlets, means for supplying an oxidizing gaseous medium to said inlets, independently operable regulating devices for said inlets and independently operable devices for said outlets.

6. A tunnel kiln having its preheating zone or zones provided with a plurality of initial inlets for a heating and oxidizing gaseous medium, disposed at intervals along one side of said zone adjacent to the lower portion of the goods space thereof, a longitudinal seriesof fans located within said zone adjacent to the lower portion of the goods space and having their axes disposed transversely of the kiln, said fans being arranged adjacent to said inlets, and constructed to draw the said medium into said zone and discharge it transversely through the goods, and cir- -culate it through and around the same entirely within the kiln, means for supplying a heating and oxidizing gaseous medium to said inlets, and means for withdrawing said medium with the gases and vapors of preheating, at separateK points longitudinally of said zone and conducting them away from the kiln. A

7. A tunnel kiln having its preheating zone or zones provided with a plurality of initial inlets for a heating and oxidizing gaseous medium disposed at intervals along one side of said zone adjacent to the lower portion of the goods space thereof, a longitudinal series of fans located within said zone adjacent to the lower portion of the goods space and having their aXes disposed transversely of the kiln, said fans being arranged adjacent to said inlets, and constructed to draw the said medium into said zone and discharge it transversely through the goods, and circulate it through and around the same entirely within the kiln, means for supplying a heating and oxidizing gaseous medium to said inlets, said zone being provided with a longitudinal series of outlets for conducting said medium and the gases and vapors of preheating away from the kiln, on the side opposite from said inlets, and independently operable means for regulating the amount of said medium circulated, located at different points longitudinally of the said zone.

8. A tunnel kiln having its preheating zone or zones provided with a plurality of initial inlet-s for a heating and oxidizing gaseous medium, disposed at intervals along one side of said zone adjacent to the lower portion of the goods space thereof, a longitudinal series of fans located within said zone adjacent to the lower portion of the goods space and having their axes disposed transversely of the kiln, said fans being arranged adjacent to said inlets, and constructed to draw the said medium into said zone and discharge it transversely through the goods, and circulate it through and around the same entirely within the kiln, means for supplying a heating and oxidizing gaseous medium to said inlets, said fans having each a capacity greater than necessary to draw said medium into said zone, enabling them to effect the recirculation thereof entirely within the main chamber of. said zone, said zone beingr provided with a series of outlets on the opposite side of said goods space from Vsaid inlet., and independently operable means for regulating the amount of medium circulated in said zone. located at intervals longitudinally of said zone.

9. A tunnel kiln having its preheating zone or zones provided with a plurality of initial inlets fora heating and oxidizing gaseous medium, disposed at intervals along one side of said zone adjacent to the lower portion of the goods space thereof, a longitudinal series of fans located within said iii transverselyV of the kiln, said fans being ar-Y ranged @adjacent-to said inlets, andronstructed to draw the said medium into; said zone and discharge ittransverselythrough the goods, and circulate it through and around the same, entirely within Ithe kiln, means for supplying a heating and oxidizing gaseous mediuinto said inlets, means for withdrawing-said medium`with vthe gases and vapors of prelieatingat separated vpoints o longitudinally of said, :tone and conducting them away from the kiln, and means for independently controlling the speed of said fans/ 'f 10.A tunnel kiln having its preheating Zone or Zonesprovided with a plurality of initial inlets for a heating and oxidizing gaseous medium, disposed at intervals along one side of said Zone adjacent to thelower portion of the goods spacethereof, a longitudinal series of fans locatedwithin said- Zone Aadjacent :to the lower portion of the goods space and having their axes disposed transversely ofthe kiln, said fans being arranged adjacent tosaid inlets, and constructed to draw the said medium into said zone and discharge it transversely through the goods, and circulate it through and `around the same entirely within the kiln, means for supplying a heating and oxidizing gaseous medium to said inlets` saidzone heingprovided witha longitudinal series of outlets for conducting said medium andgthej gases and vapors of preheating away from Vthe kiln, Vmeans for independently regulating the speed ofrsaid fans, and independently operable means for regulating the amount of said medium circulated in said Zone located at Aintervals longitudinally of said Zone.

l1. A` tunnel kiln provided with aligned preheating, iiring and cooling zones andY goods conveying means movable successively therethrough, said cooling Zone being provided with air `inlets and air outlets at' intervals longitudinally thereof, said preheating zone being provided withinitial inlets located at intervals Ylongitudinally thereof, a series of gas propelling mechanical devices located at intervalsY longitudinally of and atione side of the preheating zone adjacent to the lower por.- tion of the goods space thereof for propelling the -air `admitted through said initial'v inlets transversely ofthe preheating Zone, means' for conducting the heated air from the outlets vof a cooling zone of the kiln to the initial inlets of a preheating Zone of the kiln,. and means for withdrawingthe air together with vaporsuand gases of preheating, from said preheatingrzone. ,i Y

l2. A tunnel kiln provided` with aligned l `reheatinff firin and coolindzones and Ooods ,C7 D Y b conveying means movable successively therethrough, said cooling` zone. being provided ing zone thereof.

with `airrinlets and airoutlets at intervals longitudinally thereof, said vpreheating Zone being lprovided with initial inlets located at jintervals longitudinally thereof, a series of fans ,located'at intervals longitudinally of andV at one side of the preheating Zone adjacent tothe lower portion of thegoods space thereof and in operative relation ywith said initial inlets, and constructed to discharge the air entering through said initial inlets transversely of said Zone, means for independently regulating said initial inlets .to maintain a predetermined rising heat curve in the preheating zone and control the voxidation ofthe ware, and means for conducting heated air from the outlets of a coolingxzone of the kiln tothe initial inlets of a preheat# lBfAi tunnel'kiln provided with aligned preheating, `firing and cooling Zones and goods conveying meansmovable successively longitudinally thereof, said preheating zone being provided with initial inlets located at intervals longitudinally thereof, a series of fans located atrintervals longitudinally of andfat one sideof the. preheating zone adjacent to the lower portion of the goods space thereof andin operative relation with said initial inlets,rand constructedto discharge the air entering through said'initial inlets transversely of said Zone, means Vfor independentlyA regulating said 'initial inlets to maintain a predeterminedrising vheat curve intlielpreheating zone and control the. oxidation of the ware, means for conducting heated air from the outlets of a cooling Zone of the kiln to the initial inlets of a preheating zone thereof, and independently operable means located at different points longitudinally of the cooling'zone for controlling the amount of air entering the same for maintaining a descendingl cooling curve in the coolingzone 4lll. Atunnel Vkiln provided with aligned preheating, iiring and cooling A"Zonesjand goods conveying' means movable successively therethrough, said Vpreheating zzone being vprovided with air forcing means for effecting a circulation in the preheating zone, and

ly' therethrough, gas propelling means in said lDO goods conveying means movable successiveL preheating Zone for eifecting a circulation therein, and meanslfor connecting `portions ofsaid preheating zone adjacent to said gas propelling means with portions of a cooling zone ofthe kiln, for enabling said gas propelling means to withdraw `gaseous material from the cooling zone. i

16,. `A tunnel 4kilnprovided ywith aligned 

